Krill oil, made from small marine crustaceans called Krill (Euphausia superba), has become a popular source of omega-3 fatty acids. Unlike fish oil supplements, where omega-3 fatty acids are mainly bound to triglycerides, krill oil contains a significant proportion of omega-3 esterified into phospholipids (~40-60%). It appears that this form of omega-3 has a greater level of bioavailability (a measure of absorbancy and availability to the target tissue) and biological activity than fish oils. Krill oil also contains a powerful antioxidant – astaxanthin - that is believed to increase the anti-inflammatory effect of Krill oil. Research shows that krill oil may be beneficial for the regulation of cholesterol levels, some metabolic disorders, inflammation and symptoms of arthritis, premenstrual symptoms, brain health, heart health and colitis.

Krill oil appears to have a number of health benefits. Research suggests it may be beneficial for: 1) the symptoms and treatment of arthritis; 2) decreasing inflammatory markers like C-reactive protein (CRP); 3) regulation of cholesterol by lowering LDL-C and raising HDL-C (good cholesterol) levels; 4) modulating a number of metabolic pathways and defective metabolism; 5) heart protective effect; 6) possible brain protective effect; 7) increasing the levels of the omega-3 DHA in the; 8) management of emotional and physical symptoms of premenstrual tension; 9) treatment of colitis; 10) its potent antioxidant potential. Krill oil appears to have a number of health benefits and research suggests it may be of greater benefit and have a wider spectrum of effects than fish oil.

Krill oil and metabolic syndrome/obesity
A number of studies have shown that Krill oil may be beneficial in the treatment of metabolic disorders (Banni et al., 2011; Batetta et al., 2009; Burri et al., 2011;Piscitelli et al., 2011; Tandy et al., 2009). Researchers found that the addition of Krill oil to the diets of obese mice (induced by a high fat diet) improved several metabolic disturbances and reduced endocannabinoids levels (Piscitelli et al., 2011) - endocannabinoid levels are known to increase following the consumption of fatty foods, and once eleveated they appear to impel us to eat more fatty foods. The endocannabinoid system is believed to play an important role in the control of appetite, food intake, energy balance and body composition. Overeating/obesity can cause the endocannabinoid system to become overactive which can affect feedback mechanisms and disrupt energy and hormonal homeostasis (Banni et al., 2011; Batetta et al., 2009; Di Marzo 2008; Matias et al., 2008; Piscitelli et al., 2011;). Since krill oil appears to reduce endocannabinoid levels (Banni et al., 2011; Piscitelli et al., 2011) it may be beneficial in the treatment of obesity-related metabolic disturbances.

Research looking at the effect of fish oil and krill oil on gene expression and metabolic pathways found that krill oil significantly increased the level of gene expression and metabolic pathways when compared with fish oil (Burri et al., 2011). The researchers found that krill oil had a greater effect on gene expression than fish oil - krill oil increased gene expression in 4,892 genes, whereas omega-3s from fish oil only increased gene expression in 192 genes. In fact there were 52 metabolic pathways that were significantly changed by krill oil with only four changed by fish oil and all four of these pathways were also modulated by krill oil. The researchers stated that krill oil was more bioactive than fish oil in terms of gene expression within the liver. The researchers found that krill oil was able to exert a regulatory effect on liver metabolism including the biosynthesis of lipids and cholesterol, glucose metabolism, and fatty acid metabolism (Burri et al., 2011).

Krill oil and blood lipid/cholesterol levels
A number of studies have found that krill oil is beneficial in the regulation of blood lipids (Batetta et al., 2009; Bunea et al., 2004; Ferramosca et al., 2012; Fosshaug et al., 2011; Tandy et al., 2009; Zhu et al., 2008). Krill oil appears to be more effective in the treatment of raised blood cholesterol than fish oil with approximately 3x greater reduction in total cholesterol level compared with fish oil (Bunea et al., 2004). The researchers found that a daily dose of 500mg of krill oil may be effective for longer term usage. In another study krill oil significantly decreased total cholesterol levels, triglyceride levels, and serum LDL-cholesterol whilst slightly increasing the levels of HDL-Cholesterol (good cholesterol) (Zhu et al., 2008). A recent animal study also found that krill oil was more effective at reducing levels of liver triglycerides and cholesterol than fish oil (Ferramosca et al., 2012).

Krill Oil and heart protective effect
Krill oil supplementation has been shown to provide a protective effect in the heart (Fosshaug et al., 2011). In this study supplementation with krill oil was found to increase the levels of both EPA and DHA in the heart. The researchers found that supplementation with krill oil prior to a heart attack provided a level of protection against some of the damage caused by a heart attack.

Krill oil supplementation and DHA levels in the brain.
Researchers have demonstrated significant increases in the levels of the omega-3 fatty acid, docosahexaenoic acid (DHA), in the brain following Krill oil supplementation (Di Marzo et al., 2010). The researchers did not find any significant increase in DHA levels in the Brain following fish oil supplementation and therefore it appears that omega-3 esterfied to phospholipids may have greater bioavailability and be able to cross the blood brain barrier more easily than omega-3 from fish oil.

Krill Oil and Brain Health
Krill oil contains significant amounts of DHA which is known to be a major component of membrane phospholipids of the nervous system and is important for brain function and metabolism, and appears to have a neuroprotective effect (Rapoport et al., 2011; Bazan 2009; Bazan 2003;Salem et al., 2001;). Krill oil also provides a source of phospholipids – a major component of all cell membranes including the nerve fibres in our brains.

Researchers have found that DHA provides a level of neuroprotection (Mayurasakorn et al., 2011) and recently lower levels of red blood cell DHA - an important indicator of DHA intake (O'Brien et al., 2009) - were found to be associated with smaller brain volumes (Tan et al., 2012). Since the concentration of DHA in the brain is dependent on dietary intake, it is important that sufficient DHA requirements are met by either adequate dietary intake of through supplements like krill oil.

Krill oil is also a source of astaxanthin, a powerful antioxidant, that is believed to pass through the blood brain barrier. Researchers have found that astaxanthin significantly inhibits free radical generation and has been found to have a neuroprotective effect (Liu and Osawa 2009; Shen et al., 2009; Lu et al., 2010). The neuroprotective effect of asataxanthin appears to be due to a combination of its antioxidant activity, anti-inflammatory activity, mitochondrial protection and improving mitochondrial function.

Krill oil arthritis and anti-inflammatory markers
Krill oil appears to inhibit the inflammation associated with arthritis, may alleviate some of the arthritis symptoms, and could inhibit the development of arthritis (Deutsch, L 2007;Ierna et al., 2010;). In an animal study krill oil supplementation significantly inhibited the development of arthritis (Ierna et al., 2010;). The researchers found that Krill oil significantly reduced cartilage erosion, the thickening of the synovial membrane, and was found to be more effective than fish oil. In fact the Krill oil was found to reduce the severity of arthritis by about 50%. The researchers suggest that the antioxidant, astaxanthin, may contribute to the beneficial effects of krill oil on arthritis through its anti-inflammatory effect.

Krill oil appears to significantly inhibit inflammation with daily doses of just 300mg (Deutsch, L 2007). In this study krill oil reduced C-reactive protein (CRP) – one of the most useful biomarkers of inflammation - which is known to be increased in inflammatory conditions like rheumatoid arthritis. In fact elevated CRP appears to increase the risk of a number of diseases including heart disease, high blood pressure and diabetes. Therefore any reduction in CRP by krill oil could be beneficial in the treatment/prevention of inflammatory related diseases. Current research suggests that krill oil, through a combination of astaxanthin and omega-3s, possesses potent anti-inflammatory properties.

Krill Oil Bioavailability
A number of studies have demonstrated the improved bioavailability of krill oil when compared with fish oil (Schuchardt et al., 2011; Ulven et al., 2011; Burri et al., 2011). Researchers have demonstrated that the omega-3 fatty acids were absorbed more efficiently from Krill oil when compared with the same dose of omega-3 from fish oils (Schuchardt et al., 2011). It has been suggested that the enhanced bioavailability of omega-3s in krill may be due to the esterification of phospholipids and omega-3 which may improve its uptake in the intestines and across cell membranes. Krill oil has also been found to contain relatively high concentrations of EPA and DHA as free fatty acids - 22% of total EPA and 21% of total DHA were found to be in the free fatty acid form rather than bound to phospholipids (Schuchardt et al., 2011). The researchers suggested that the presence of relatively high levels of omega-3 as free fatty acids may improve the bioavailability of the EPA and DHA in krill oil. Therefore it may be a combination of the omega-3s bound to phospholipids and the omega-3s as free fatty acids that enhance its bioavailability compared with fish oil.

Krill oil's antioxidant activity
Krill oil contains astaxanthin, a potent antioxidant with anti-inflammatory properties (Fassett and Coombes 2011, Riccioni et al., 2011), which is believed to be responsible for some of the beneficial anti-inflammatory effects seen with krill oil (Piscitelli et al., 2011; Ierna et al., 2010;). Research suggests that astaxanthin may be beneficial for cardiovascular health (Fassett and Coombes 2011, Riccioni et al., 2011) and may also play a role in increasing HDL-cholesterol – the good cholesterol – and decreasing triglyceride levels (Ulven et al., 2011; Yoshida et al., 2010).

Krill Oil and colitis
Krill oil appears to have a potential protective effect against colitis - inflammation of the colon - and may be beneficial in its treatment (Grimstad et al., 2012). Krill oil may be beneficial in th treatment of colitis due to it's anti-inflammatory and anti-oxidant properties.

Krill Oil and premenstrual symptoms
Another area of interest is in the use of krill oil for the treatment of premenstrual symptoms. Research suggests that Krill oil may help to reduce the the symptoms (physical and emotional) of premenstrual syndrome (PMS) more effectively than fish oil (Sampalis et al., 2003). The improved effectiveness of the fish oil could be to the greater bioavailability of krill oil omega-3s and the presence of phospholipids which help to maintain cell membranes and hormone activities.

Krill oils anti-cancer properties
Krill oil appears to possess some anti-cancer properties (Zhu et al., 2008). In a study (Zhu et al., 2008) looking at the exposure of human cancer cells to different concentrations of krill oil for 48 hours, found that cancer cell growth was inhibited in a dose dependent manner (i.e. the greater the dose the greater the inhibition). Krill oil was also found to inhibit cancer cells in a time dependent manner with more pronounced inhibition occuring at 72 hours and 120 hours post treatment.

Research has found that Krill oil has a greater bio-availability and bio-activity than fish oils. Some of the beneficial effects attributed to krill oil include: regulation of cholesterol levels, modulation of metabolic pathways and metabolic disorders, reduces inflammation, aids symptoms and progression of arthritis, alleviates some premenstrual symptoms, may improve brain and heart health, possible benefit for colitis.

Research has generally looked at the effects of a daily dosage of between 1-3g of krill oil. The beneficial effects appear to increase in a dose dependent manner (i.e. greater benefits were seen with the higher doses. However, researchers found that a maintenance dose of just 500mg daily was significantly effective for longer term regulation of blood lipids.

Research has found that Krill oil appears to be safe and well tolerated (Ulven et al., 2011; Batetta et al., 2009;Maki et al., 2009; Deutsch, L 2007). Because krill oil comes from a marine crustacean, people with seafood allergies should avoid krill oil. Also people with blood disorders or those taking blood thinning medication, anti-inflammatory drugs, or blood thinning herbs like ginkgo biloba should consult their health/medical practitioner before taking krill oil.